Youth Court Offending Rates

Abstract | Introduction | Method | Results | Conclusion | References | Appendix 1 Area data | Appendix 2 Raw data

Method

The nature of the methodology and the principal steps taken are dealt with under the following headings:

1. Determining the number of distinct cases and distinct individuals that are related to charges laid in each Youth Court for each year;
2. Determining the geographical areas served by each Youth Court in a manner that can be matched with population information;
3. Obtaining population data for 14-16 year olds for the whole country and for each
Youth Court; and
4. Data analysis and presentation.

1 Determining distinct cases and distinct individuals appearing in Youth Courts

The Ministry of Justice provided data on charges, distinct cases and the distinct offenders
appearing in each Youth Court for each year from 1987/88 to 2000/01. The overall data for
each Youth Court is presented in Appendix 2 as Tables B1 and B2.

2 Determining geographical areas served by each Youth Court

The Department for Courts does not have geographical boundaries for the Youth Court areas.
However, the cases coming before them are effectively defined by the Police stations when
they lay charges and Police do have information on the TA (Territorial Authority) areas
covered by each Police Station. These TAs are areas reported on by the census and thus
population information from Statistics New Zealand can be obtained for each TA. The Office
of the Commissioner of Police supplied a list of police stations and associated TA areas. A
number of police officers throughout the country provided information about which courts the
stations in their general area or district referred Youth Court cases to.

A total of 66 different Youth Courts are listed in Appendix 2 (see Table B3). For many of
these, the numbers are too small for reliable comparisons from year to year. As a result of
discussions with the Department for Courts these 66 separate Youth Courts were grouped into
16 Youth Court Areas for the purpose of statistical profiling. Table B3 in Appendix 2 sets out
the details of this recategorisation and includes details of the relevant TAs.

3 Obtaining population data

The final set of information needed in order to develop data on rates was information on the
population in each area by age groups. National population estimates for each year of age are
published annually and these enable rate comparisons to be made nationally for the data
provided for each year. However, these estimates are not broken down by TAs and it was
necessary to find another source of age information for each TA in the intercensal years. Data
on the numbers of 14-16 year olds in each TA was obtained from Statistics New Zealand for
each of the four most recent censuses (1986, 1991, 1996, 2001). This data was graphed and
estimates of numbers in intercensal years were made by reading off data from trend lines on the graphs of the population for each Youth Court Area from 1986 to 2001. The final data for
each year for each Youth Court Area are set out in Table B4 of Appendix 2.

4 Data analysis and presentation

Rates of distinct cases and distinct individuals were calculated for each year for each Court
area.[2]. These area data are presented in the form of numbers in Appendix 1 as Tables A1-
A16 and as graphs in Appendix 1 (Figures A1a-A16a). Similarly, rates have been calculated
for girls and boys, and for Maori, Pacific and European ethnicities. These data are presented
in graphs in the Results section below (see Figures 2-6) and as tables in Appendix 2 (see Tables B5 and B6).

Rates for each area of cases and offenders were compared to the national average rate of cases
and offenders for each year. Charts showing these data for each area are included in
Appendix 1 (see Figures A1b to A16b). These data indicate how each area differs from the
national average over the period 1988 to 2001.

In addition, a ratio of the differences between distinct cases and distinct young offenders was
calculated for each year. This can be called the “within year reappearance ratio” (WYRR). It
can be used as an indicator of success in preventing reoffending. However it is likely to be
affected by mobility and police practice in referring relatively non-serious offences in different areas (see Figures A1c-A16c in Appendix 1).

Limitations of the data

This data will provide information previously unavailable, but there will still be a number of
limitations to it:

• The TAs, which are the source of population data estimated for Youth Court areas, have been subject to some changes over the four censuses and these may be a source of error;
• The population estimates for inter-censal years for each Youth Court area will not be entirely accurate and these could also be a source of error; and
• Despite the amalgamation of smaller courts with adjacent ones, numbers of cases are still quite small in any particular year in many areas so that apparent differences between areas may not be statistically significant

Nevertheless, these data will be much more robust than the data on number of charges laid in
each Youth Court, which was all that was previously available. It is also unlikely that any of
the above limitations will result in serious errors in comparing larger court areas with one another and in making comparisons across time.

Footnote

2 Data has also been collected on numbers of charges but is not reported in this paper. Reasons
for this are the possible unreliability of charge information as an indicator of offending, as described in the discussion of Figure 1 in the results section of this report.